May I use FME Objects in Startup / Shutdown Python Script?

Hi Takashi,

 

 

I have seen this warning a lot but never really experienced any instability that I could link to this issue.

 

 

However, the warning seems to disappear if you manually destroy your fmeobject class instances before your script terminates. Example:

 

 

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import fmeobjects myobj = fmeobjects.FMELicenseManager()   print "hello world"

 

# Manually free the FMELicenseManager instance del myobj

 

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It seems a bit non-Pythonic to me that this is necessary in FME, but there you go. You could perhaps flag this as an issue with Safe.

 

 

Tested using FME2013sp3

 

 

David

Sharing the answer from Safe.

 

 

Answer from Safe "The Python FMEObjects API is a wrapper around the native C++ API, and so requires some garbage collection not normally done in Python. Setting your FMEObjects objects to None to destroy them once you no longer need them will prevent the FMESessions warning. This is not a major issue when running FME Desktop, since FME will clean up after itself when it shuts down, but can cause problems in FME Server, where FME runs constantly."   Test with FME 2013 SP3, Startup / Shutdown Python Script ----- import fmeobjects   # Create an FME object. licMan = fmeobjects.FMELicenseManager()   # Do something using the object   # Destroy the object (flag on garbage collection) licMan = None ----- ... the warning message disappears.

 

  Conclusion When we use FME objects in Startup / Shutdown Python Script, we should explicitly flag on garbage collection (assign None) to destroy them after using. If we didn't destroy them, - It will not be a major issue when running FME Desktop - It can cause problems when running FME Server

 

 

I think "del" statement may be also used to destroy an object.

In short; assume a variable is the last one which refers to the object, the Python garbage collector seems to collect it (and destroy it as soon as possible) at these points: - the variable has become to refer to another object (e.g. None). - the variable has been deleted explicitly with del statement. - scope of the variable has been finished.   The mist has cleared up :-)